From "Lost Live Dead"
August 20, 1969 El Roach, Ballard, WA (updated)
Earlier I had written two posts about the Grateful Dead's performance at the Aqua Theatre in Seattle, WA on August 21 , 1969. The Aqua Theatre was scheduled for August 20 and rained out, and the three acts on the bill, The Grateful Dead, The New Riders of The Purple Sage and San Paku, all performed the next night. During the August 21 show, the Dead were joined by a flute player, which most sources have generally listed as Charles Lloyd. Much as I love Charles Lloyd, I have always found his presence in Seattle in 1969 unlikely. I posited that the guest flute player might have been a member of the opening group San Paku.
Fortunately, the former road manager of San Paku saw the post and helped resolve the mystery. Apparently, San Paku reed man Gary Larkey was indeed the guest flautist with the Grateful Dead. More importantly, Larkey recalls the name of the Seattle club where the Dead made a guest appearance: Larkey recalled it as The Roach, but following Ross's insightful research in the Comments, I am assuming it was an apparently notorious establishment called El Roach, in Ballard, a suburb just Southwest of Seattle. The exact address was 5419 Ballard Avenue NW, between 24th NW and 25th NW Avenue (not precisely McNally's "15th Street," but not far off). The tavern was a regular music venue just 2.8 miles from the site of the Aqua Theatre, so it seems like a perfect fit.